Tomokui Kanata has been re-incarnated in the weakest goblin, named Goburou, after having undergone an unfortunate death. However Goburou has retained his previous life's memories, an unusual evolution, as well as becoming strong enough to gain status boosts from eating. In this alternate world of survival of the fittest, events unfold with competent subordinates and comrades, delightful case of the tail-wagging dog...

Years ago, astronaut Byakuya left behind precious materials in the belief that his son, the scientifically-gifted Senkuu, would one day find them. In the present, the Kingdom of Science's Kohaku and Ginrou have infiltrated the harem of the Petrification Kingdom’s leader with the help of Amaryllis, a local girl. At first, their mission progresses without a hitch. Unfortunately, an error enacted by Kohaku and Ginrou leads Minister Ibara and the Island’s strongest warrior, Moz, to identify the intruding duo as enemies. Even worse, Moz tails Amaryllis when she returns to inform Senkuu of the news, discovering the scientist's secret hideout. However, Moz's agenda does not align with Ibara's—he wants to dethrone the minister and keep the petrification device for himself. If Senkuu plays his cards right, he could gain a powerful ally and win the war once and for all.

In a time when the great war between five rival races for supremacy on Earth ended with humanity's victory led by the hero Sid, the world suddenly gets "overwritten" right before the eyes of a boy named Kai. In this rewritten world, Kai witnesses humanity's defeat in the war as a result of Sid's absence—where dragons and demons now rule the land, and Kai himself has become a forgotten existence to all humans. However, after encountering the mysterious girl Rinne, Kai resolves to break free from this rewritten fate. In a world without a hero, he inherits the sword and martial skills of the hero (Sid) and challenges the powerful enemy races that dominate the land.

Striking fear into the hearts of mortals, the Demon Lord Satan begins to conquer the land of Ente Isla with his vast demon armies. However, while embarking on this brutal quest to take over the continent, his efforts are foiled by the hero Emilia, forcing Satan to make his swift retreat through a dimensional portal only to land in the human world. Along with his loyal general Alsiel, the demon finds himself stranded in modern-day Tokyo and vows to return and complete his subjugation of Ente Isla—that is, if they can find a way back! Powerless in a world without magic, Satan assumes the guise of a human named Sadao Maou and begins working at MgRonald's—a local fast-food restaurant—to make ends meet. He soon realizes that his goal of conquering Ente Isla is just not enough as he grows determined to climb the corporate ladder and become the ruler of Earth, one satisfied customer at a time! Whether it's part-time work, household chores, or simply trying to pay the rent on time, Hataraku Maou-sama! presents a hilarious view of the most mundane aspects of everyday life, all through the eyes of a hapless demon lord. [Written by MAL Rewrite]